A gangplank-ladder of this type is described for example in the Italian industrial utility model application No. 4225 B/86. The two portions of the gangplank described in this previous patent are hinged together by means of a pair of triangular plates to which pairs of actuators in the form of cylinder-pistons are fastened, hinged at one end to the said plate and at the opposite end to one or the other of the two portions of the gangplank. This configuration is particularly complex and cumbersome and, in addition, requires very many connections to the hydraulic system for controlling the actuators.
The first portion, that is the upper portion of the gangplank, is hinged to the craft and its oscillation with respect to the hull is obtained by means of a cylinder-piston system connected to the gangplank by means of a system of levers. This type of control also is complex and very cumbersome.